1. Field of the Invention
The present invention relates to an insert for a carrying strap for carrying objects by persons.
2. Background Art
Carrying objects is made easier when they can be carried by hand using a handle or when they can be carried at the body using a carrying strap.
A carrying strap has the advantage that the weight of the object is distributed over larger areas of the body. The use of two carrying straps, for example with a backpack, makes it possible to distribute the weight symmetrically over the body. In this way, heavy loads can be more easily carried.
Carrying an object can involve vertical movements and accelerations that result in additional vertical forces that act on the body of the carrier of the object. These vertical forces increase when going up a staircase, on uneven ground, or when walking fast, for example. These forces may be sensed as a hitch or an impact on the body.
For cushioning such forces it is known to provide carrying straps with an elastic section that distributes the momentum carried over to the body caused by vertical accelerations over a longer period and therefore results in a smaller force exerted on the body. For example, International Application Publication No. WO 03/007749 A1 describes a backpack with carrying straps that include such an elastic section.
When carrying heavy loads and/or in cases of strong vertical accelerations, however, there is the risk that the elastic section may be elongated too far or may be over-elongated beyond the elasticity of its material. In order to avoid this problem, it is known to limit the elongation of the elastic section, for example by an inelastic strap having ends stitched to the ends of the elastic section, as described in German Patent No. DE 299 10 127. Similar techniques for limiting the elongation of elastic sections are described in U.S. Pat. Nos. 4,827,578 and 4,976,388, and US Patent Application Publication No 2006/0163305. In addition to limitation of the elongation of a carrying strap, International Application Publication No. WO 94/16595 describes an elastic section of a carrying strap that includes several layers of different length, providing graduated cushioning of vertical forces.
Although such a limited cushioning makes it easier to carry loads, the comfort provided is confined to a specific range of vertical forces. In contrast, the forces desired to be cushioned may vary widely. A specific cushioning that is considered comfortable during walking may result, during running, in a substantially greater elongation of the elastic section, due to the stronger vertical forces, that may not be considered comfortable.
What is needed is improved elastic cushioning of a carrying strap so that adjustment to different vertical forces is possible.